In those applications where an intricate design of metal bonded to glass is desired such as on electrical resistance heating plates, microwave oven door panel shields, and the like, the procedure has generally involved application to the glass sheet of a thin coating of aluminum or other metal by known metallizing techniques. An enamel resist was then applied to the coating by silk screening and then the aluminum removed in those areas not protected by the enamel resist by use of caustic or acid etching baths. Subsequent neutralizing and washing are then used to neutralize the chemicals of the etching bath. The product thus produced may, if desired, be further totally coated with a high temperature lacquer or the like to render the exposed glass areas opaque and to protect the intricate metal design from the atmosphere.
It will be appreciated that while this method has proved successful, it does involve costly and intricate steps utilizing caustic and acid etching baths, neutralizing baths and the like. It also requires the use of costly silicone enamel resistant paint and frequently results in pinholes in the aluminum pattern by the etching action of the baths when the silicone resist is not perfectly applied, this system also presents difficulties with respect to control of the accuracy of the grid line width.